In the sticks we get 25GB. So, quite a crunch. Here's what I've done.
I set our Roku device to force lower quality streams. It now uses 270MB for an hour of video. We were using around 1.5 GB. That's 82% less! Before I figured out how to set it at the Roku level I set the streaming quality at Netflix, which could help someone reading who watches on their computer instead of the TV. But we also watch Amazon so I needed a deeper solution. By the way, to access the settings page for your Roku using the remote, hit Play 5x, then Rewind 3x, then Fast Forward 2x, like on an old Nintendo. I chose 0.6 Mbits and it's fine for our television size and viewing distance.
Now, our video wasn't all of our internet but it was a substantial portion. I also set Youtube on every computer to "I have a slow connection." That helps. I will have to curb my Google Plus habit (sob!) and switch to Twitter for all my inane microblogging needs. And there will be more here too, no doubt.